Secondary electrospray ionization (SESI)ion mobility spectrometer (IMS)was applied for detection of acetone, isoprene and ethylbenzene, the representatives of volatile organic compounds (VOCs),which are closely related to disease in breath gas.The SESI source with the direction of the sample gas flow parallel to the ion stream was designed and the ionization efficiency was improved.The stable electrospraying was obtained by the cooling effect of sample gas to electrospraying liquid.The SESI-IMS system was constructed and the effects of parameters such as temperature of ionization region, electrospraying liquid flow rate and sample gas flow rate were analyzed.The 3 times noisebased detection limits of acetone, isoprene and ethylbenzene were calculated to be 38.8 ng/L, 68.9 ng/L and 46.9 ng/L respectively when the conditions of temperature of ionization region is 175 ℃, electrospraying liquid flow rate is 1 μL/min and sample gas flow rate is 200 mL/min.The SESI-IMS system has the potential application for detection of VOCs in breath gas.%针对呼出气体中与疾病密切相关的丙酮、 异戊二烯、 乙苯等气体, 研究了用于挥发性有机物(Volatile Organic Compounds, VOCs)检测的二次电喷雾电离(Secondary Electrospray Ionization, SESI)-离子迁移率谱(Ion Mobility Spectrometry, IMS)系统.设计了样品气体流向与离子漂移方向相同的SESI电离源结构, 在提高电离效率的同时对电喷液起到冷却作用, 有利于保持电喷雾过程的稳定.搭建了SESI-IMS系统, 分析了离化区温度、 电喷液流量、 样品气体进样流量等参数对系统检测结果的影响.在离化区温度175 ℃、 电喷液流量1 μL/min、 进样流量200 mL/min的条件下, 系统对丙酮、 异戊二烯和乙苯的3倍噪声检测限分别为38.8, 68.9和46.9 ng/L, 具有应用于呼出气体VOCs检测的潜力.
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